Downloading data via computer networks such as the Internet is becoming increasingly popular. Downloaded data may include movies, music recordings, books, and other media. There are different types and sizes of memory storage devices available to users for storing and accessing the downloaded information. Devices used by consumers for playing music and movies range from home theatre systems to highly portable palmtop devices. Accordingly, there is a need to provide a storage device and storage medium that is compact and portable, yet capable of storing and transmitting large amounts of data for real-time playback. The storage device must also interface with a wide variety of hosts such as personal computer systems, televisions, audio systems, and portable music players. Further, it is important for the storage device to protect content on the storage medium using a digital rights management scheme.
Write Once Read Many (WORM) storage media may be used to meet these requirements. One example of WORM storage medium is disclosed in U.S. patent application Ser. No. 09/560,781, entitled, “WRITEABLE MEDIUM ACCESS CONTROL USING A MEDIUM WRITEABLE AREA”, filed on Apr. 28, 2000, assigned to the common assignee and is incorporated in its entirety herein by reference.
Magnetic and optical data storage systems typically include a controller which interfaces the host device to the data storage device. The controller receives commands and data from, and provides status and data to, the host device. In response to the commands, the data storage device controller provides signals which control the writing of data to and reading of data from the storage medium.
In the prior art, the host device includes a disk operating system or file management system which interfaces file commands of a user (e.g., through user programs) and the commands recognized by the controller of the storage device. Tasks performed by known file management systems include keeping a directory of the location of all files of information data on the storage disk, and keeping track of remaining free space on the disk. In magnetic data storage systems, data written to the magnetic disk can be erased and rewritten, and therefore updated. The file management system therefore causes directory data to be written to predetermined locations on the magnetic disk. As files of information data are added to the magnetic disks, the file management system simply adds directory data to the reserved directory region. If a previously written file is updated, the file management system can erase and update previously written directory data.
Due to the characteristics of WORM data storage systems, the file management systems typically used with magnetic data storage systems are incapable of interfacing the host computer to a WORM disk drive. As a result, a separate file management system must be included within the host computer for WORM data storage systems. In WORM optical disk drive systems, for example, data can only be written once to any location on the optical disk. Directory data cannot, therefore, be updated on previously written locations. Each time one or more new files of information is written to the optical disk of the WORM optical data storage system, the file management system must write directory data associated with these files at a new location on the optical disk. The file management system should also write directory data in a form which enables the most recent versions of updated files to be found.